From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4E91DCC6B03 for ; Tue, 13 Oct 2026 07:53:18 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C6FD410F57D; Tue, 13 Oct 2026 07:53:00 +0000 (UTC) X-Greylist: delayed 987 seconds by postgrey-1.36 at gabe; Tue, 13 Oct 2026 06:54:46 UTC Received: from spark.kcore.it (spark.kcore.it [49.13.27.68]) by gabe.freedesktop.org (Postfix) with ESMTPS id BEC8310F4C1 for ; Tue, 13 Oct 2026 06:54:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=kcore.it; s=spark; h=References:In-Reply-To:Content-Type:MIME-Version:Message-ID: Subject:Cc:To:From:Date:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:Resent-Date; bh=sVVl0YKFWEeW8zool1E3ui30P//TcmWvC+2pSRfUDwg=; b=L3nruNbrflVyJuABlaTnsXyLX+ Dz/ewcCkhMbEar/DcxvPr0xhZPtDNcPJIS60bes7GHAMx/sLRsfddroTtokalpKeiKgAn8s5Ma9wl Fmwh/bfWrWZ3hB3M5f397rqo1QQ79Et5UIJQxkJMX53ah2ALOvnlnGwTgp7W6HVWP0ME=; Received: from mnencia by spark.kcore.it with local (Exim 4.100.1) (envelope-from ) id 1xGW9L-00000000Ghm-0Cei; Tue, 13 Oct 2026 08:38:11 +0200 Date: Tue, 13 Oct 2026 08:38:11 +0200 From: Marco Nenciarini To: dri-devel@lists.freedesktop.org Cc: lyude@redhat.com, David.Francis@amd.com, jani.nikula@linux.intel.com, xiaolu.xie@intel.com Subject: Re: [PATCH v2] drm/dp/mst: reject DPCD read/write on ports with ddps=0 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260920022144.2209244-1-xiaolu.xie@intel.com> References: <016616a21018b45177f134ab001edc6decb4a8ec.camel@redhat.com> <20260920022144.2209244-1-xiaolu.xie@intel.com> X-Mailman-Approved-At: Tue, 13 Oct 2026 07:52:59 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Tested-by: Marco Nenciarini Tested on a Dell Pro Max 16 (Arrow Lake-P) with Debian 7.2.6 and a Dell WD19DC dock with two MST sinks, i915 driving the dock over TBT-alt. Before the patch, every DPMS wake showed REMOTE_DPCD_READ BAD_PARAM NAKs on the empty downstream port. With the patch there were none across three DPMS off/on cycles. Both sinks were enumerated and lit up normally. The separate black screen after a long DPMS off is not affected by this patch. It is tracked in drm/i915/kernel#16901. -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEfCO4BD5l0pgKIbbiWJ8D8BulUDgFAmrN0bMACgkQWJ8D8Bul UDixdw//Vwdq5quU2oGIGXJU1YSMbBKEjxkqaRhBR/QiEsy93lwIlnps2UT8fwh3 EmeyaM+htA1kBzPsD8CZEdUIHDoo7U6lIDEBNeVFAkTjcg77NxIngsZ1ooqsTkcz OuZGNVzCgmkqk045vcCoqXdqDUn+KFC68WtiSvOUtgGkeFtnsew2LPN3Vz2NA+xi QzhKJv+QtpJJYgMQUfMZeRKR48IO9wlKYD3zSQW7g94Sh61Y+quVYaGaz7j5pIGo PQ/AZPCa2iATbBnl29KaTOClMvRAEZ+lXhoZ6FpbBsZflO5Rqf8EH+lyR6J3rbgu xVJ+Zm+xvEYnYVtAnVtr8uTHY23qQV4i/iYK/E0/CbeJUzELynF5Svz6WQL/Oqyc F1fjmNrLBklmeeCZnlAveV+AX9OKq+1xzGizeKexu88x3jJAihfMbojdgejl6rke P+0KB1w1CKAFHXmB9/dg1cfy1YJ9j0daMv64uCv7DlioWHFz2qMVX2A+6MRqwzDR vGCfJwds+f6opnpvODW/SizUd0bMS1FKqY26gCX8Bmr4DaIGUYjzOqq1H1EHbNtp S0ul/bqDaIPZPzP3oyRDz/XxLzWn2iGgMiBIRT5fQg5K+6H0/1AQ53PaCmm3809X mU60tVwTqbNeHetSdMARfrr8rudhjksChNxQQEeMAlmWFpXaUQ0= =Mkwe -----END PGP SIGNATURE-----